/**
 * Copyright (c) 2005-2011 huisou.com
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 
 * $Id: HibernateDao.java 1547 2011-05-05 14:43:07Z Valiant $
 */
package com.chenzehe.java.core.orm.hibernate;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.criterion.CriteriaSpecification;
import org.hibernate.criterion.Criterion;
import org.hibernate.criterion.Disjunction;
import org.hibernate.criterion.MatchMode;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Projection;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;
import org.hibernate.impl.CriteriaImpl;
import org.hibernate.transform.ResultTransformer;

import com.chenzehe.java.core.orm.Page;
import com.chenzehe.java.core.orm.PageRequest;
import com.chenzehe.java.core.orm.PageRequest.Sort;
import com.chenzehe.java.core.orm.PropertyFilter;
import com.chenzehe.java.core.orm.PropertyFilter.MatchType;
import com.chenzehe.java.core.utils.AssertUtils;
import com.chenzehe.java.core.utils.ReflectionUtils;

/**
 * 封装SpringSide扩展功能的Hibernat DAO泛型基类.
 * 
 * 扩展功能包括分页查询,按属性过滤条件列表查询.
 * 
 * @param <T>
 *            DAO操作的对象类型
 * @param <ID>
 *            主键类型
 * 
 * @author Valiant
 */
public class HibernateDao<T, ID extends Serializable> extends SimpleHibernateDao<T, ID> {
	
	public static final String	DEFAULT_ALIAS	= "x";
	
	/**
	 * 通过子类的泛型定义取得对象类型Class. eg. public class UserDao extends HibernateDao<User, Long>{ }
	 */
	public HibernateDao() {
		super();
	}
	
	public HibernateDao(Class<T> entityClass) {
		super(entityClass);
	}
	
	// -- 分页查询函数 --//
	
	/**
	 * 分页获取全部对象.
	 */
	public Page<T> getAll(final PageRequest pageRequest) {
		return findPage(pageRequest);
	}
	
	/**
	 * 按HQL分页查询.
	 * 
	 * @param pageRequest
	 *            分页参数.
	 * @param hql
	 *            hql语句.
	 * @param values
	 *            数量可变的查询参数,按顺序绑定.
	 * 
	 * @return 分页查询结果, 附带结果列表及所有查询输入参数.
	 */
	public Page<T> findPage(final PageRequest pageRequest, String hql, final Object... values) {
		AssertUtils.notNull(pageRequest, "pageRequest不能为空");
		
		Page<T> page = new Page<T>(pageRequest);
		
		if (pageRequest.isCountTotal()) {
			long totalCount = countHqlResult(hql, values);
			page.setTotalItems(totalCount);
		}
		
		if (pageRequest.isOrderBySetted()) {
			hql = setOrderParameterToHql(hql, pageRequest);
		}
		Query q = createQuery(hql, values);
		
		setPageParameterToQuery(q, pageRequest);
		
		List result = q.list();
		page.setResult(result);
		return page;
	}
	
	/**
	 * 按HQL分页查询.
	 * 
	 * @param page
	 *            分页参数.
	 * @param hql
	 *            hql语句.
	 * @param values
	 *            命名参数,按名称绑定.
	 * 
	 * @return 分页查询结果, 附带结果列表及所有查询输入参数.
	 */
	public Page<T> findPage(final PageRequest pageRequest, String hql, final Map<String, ?> values) {
		AssertUtils.notNull(pageRequest, "page不能为空");
		
		Page<T> page = new Page<T>(pageRequest);
		
		if (pageRequest.isCountTotal()) {
			long totalCount = countHqlResult(hql, values);
			page.setTotalItems(totalCount);
		}
		
		if (pageRequest.isOrderBySetted()) {
			hql = setOrderParameterToHql(hql, pageRequest);
		}
		
		Query q = createQuery(hql, values);
		setPageParameterToQuery(q, pageRequest);
		
		List result = q.list();
		page.setResult(result);
		return page;
	}
	
	/**
	 * 按Criteria分页查询.
	 * 
	 * @param page
	 *            分页参数.
	 * @param criterions
	 *            数量可变的Criterion.
	 * 
	 * @return 分页查询结果.附带结果列表及所有查询输入参数.
	 */
	public Page<T> findPage(final PageRequest pageRequest, final Criterion... criterions) {
		AssertUtils.notNull(pageRequest, "page不能为空");
		
		Page<T> page = new Page<T>(pageRequest);
		
		Criteria c = createCriteria(criterions);
		
		if (pageRequest.isCountTotal()) {
			long totalCount = countCriteriaResult(c);
			page.setTotalItems(totalCount);
		}
		
		setPageRequestToCriteria(c, pageRequest);
		
		List result = c.list();
		page.setResult(result);
		return page;
	}
	
	/**
	 * 在HQL的后面添加分页参数定义的orderBy, 辅助函数.
	 */
	protected String setOrderParameterToHql(final String hql, final PageRequest pageRequest) {
		StringBuilder builder = new StringBuilder(hql);
		builder.append(" order by");
		
		for (Sort orderBy : pageRequest.getSort()) {
			builder.append(String.format(" %s.%s %s,", DEFAULT_ALIAS, orderBy.getProperty(), orderBy.getDir()));
		}
		
		builder.deleteCharAt(builder.length() - 1);
		
		return builder.toString();
	}
	
	/**
	 * 设置分页参数到Query对象,辅助函数.
	 */
	protected Query setPageParameterToQuery(final Query q, final PageRequest pageRequest) {
		q.setFirstResult(pageRequest.getOffset());
		q.setMaxResults(pageRequest.getPageSize());
		return q;
	}
	
	/**
	 * 设置分页参数到Criteria对象,辅助函数.
	 */
	protected Criteria setPageRequestToCriteria(final Criteria c, final PageRequest pageRequest) {
		AssertUtils.isTrue(pageRequest.getPageSize() > 0, "Page Size must larger than zero");
		
		c.setFirstResult(pageRequest.getOffset());
		c.setMaxResults(pageRequest.getPageSize());
		
		if (pageRequest.isOrderBySetted()) {
			for (Sort sort : pageRequest.getSort()) {
				if (Sort.ASC.equals(sort.getDir())) {
					c.addOrder(Order.asc(sort.getProperty()));
				}
				else {
					c.addOrder(Order.desc(sort.getProperty()));
				}
			}
		}
		return c;
	}
	
	/**
	 * 执行count查询获得本次Hql查询所能获得的对象总数.
	 * 
	 * 本函数只能自动处理简单的hql语句,复杂的hql查询请另行编写count语句查询.
	 */
	protected long countHqlResult(final String hql, final Object... values) {
		String countHql = prepareCountHql(hql);
		
		try {
			Long count = findUnique(countHql, values);
			return count;
		}
		catch (Exception e) {
			throw new RuntimeException("hql can't be auto count, hql is:" + countHql, e);
		}
	}
	
	/**
	 * 执行count查询获得本次Hql查询所能获得的对象总数.
	 * 
	 * 本函数只能自动处理简单的hql语句,复杂的hql查询请另行编写count语句查询.
	 */
	protected long countHqlResult(final String hql, final Map<String, ?> values) {
		String countHql = prepareCountHql(hql);
		
		try {
			Long count = findUnique(countHql, values);
			return count;
		}
		catch (Exception e) {
			throw new RuntimeException("hql can't be auto count, hql is:" + countHql, e);
		}
	}
	
	private String prepareCountHql(String orgHql) {
		String countHql = "select count (*) " + removeSelect(removeOrders(orgHql));
		return countHql;
	}
	
	private static String removeSelect(String hql) {
		int beginPos = hql.toLowerCase().indexOf("from");
		return hql.substring(beginPos);
	}
	
	private static String removeOrders(String hql) {
		Pattern p = Pattern.compile("order\\s*by[\\w|\\W|\\s|\\S]*", Pattern.CASE_INSENSITIVE);
		Matcher m = p.matcher(hql);
		StringBuffer sb = new StringBuffer();
		while (m.find()) {
			m.appendReplacement(sb, "");
		}
		m.appendTail(sb);
		return sb.toString();
	}
	
	/**
	 * 执行count查询获得本次Criteria查询所能获得的对象总数.
	 */
	protected long countCriteriaResult(final Criteria c) {
		CriteriaImpl impl = (CriteriaImpl) c;
		
		// 先把Projection、ResultTransformer、OrderBy取出来,清空三者后再执行Count操作
		Projection projection = impl.getProjection();
		ResultTransformer transformer = impl.getResultTransformer();
		
		List<CriteriaImpl.OrderEntry> orderEntries = null;
		try {
			orderEntries = (List) ReflectionUtils.getFieldValue(impl, "orderEntries");
			ReflectionUtils.setFieldValue(impl, "orderEntries", new ArrayList());
		}
		catch (Exception e) {
			logger.error("不可能抛出的异常:{}", e.getMessage());
		}
		
		// 执行Count查询
		Long totalCountObject = (Long) c.setProjection(Projections.rowCount()).uniqueResult();
		long totalCount = (totalCountObject != null) ? totalCountObject : 0;
		
		// 将之前的Projection,ResultTransformer和OrderBy条件重新设回去
		c.setProjection(projection);
		
		if (projection == null) {
			c.setResultTransformer(CriteriaSpecification.ROOT_ENTITY);
		}
		if (transformer != null) {
			c.setResultTransformer(transformer);
		}
		try {
			ReflectionUtils.setFieldValue(impl, "orderEntries", orderEntries);
		}
		catch (Exception e) {
			logger.error("不可能抛出的异常:{}", e.getMessage());
		}
		
		return totalCount;
	}
	
	// -- 属性过滤条件(PropertyFilter)查询函数 --//
	
	/**
	 * 按属性查找对象列表,支持多种匹配方式.
	 * 
	 * @param matchType
	 *            匹配方式,目前支持的取值见PropertyFilter的MatcheType enum.
	 */
	public List<T> findBy(final String propertyName, final Object value, final MatchType matchType) {
		Criterion criterion = buildCriterion(propertyName, value, matchType);
		return find(criterion);
	}
	
	/**
	 * 按属性过滤条件列表查找对象列表.
	 */
	public List<T> find(List<PropertyFilter> filters) {
		Criterion[] criterions = buildCriterionByPropertyFilter(filters);
		return find(criterions);
	}
	
	/**
	 * 按属性过滤条件列表分页查找对象.
	 */
	public Page<T> findPage(final PageRequest pageRequest, final List<PropertyFilter> filters) {
		Criterion[] criterions = buildCriterionByPropertyFilter(filters);
		return findPage(pageRequest, criterions);
	}
	
	/**
	 * 按属性条件参数创建Criterion,辅助函数.
	 */
	protected Criterion buildCriterion(final String propertyName, final Object propertyValue, final MatchType matchType) {
		AssertUtils.hasText(propertyName, "propertyName不能为空");
		Criterion criterion = null;
		// 根据MatchType构造criterion
		switch (matchType) {
			case EQ:
				criterion = Restrictions.eq(propertyName, propertyValue);
				break;
			case LIKE:
				criterion = Restrictions.like(propertyName, (String) propertyValue, MatchMode.ANYWHERE);
				break;
			
			case LE:
				criterion = Restrictions.le(propertyName, propertyValue);
				break;
			case LT:
				criterion = Restrictions.lt(propertyName, propertyValue);
				break;
			case GE:
				criterion = Restrictions.ge(propertyName, propertyValue);
				break;
			case GT:
				criterion = Restrictions.gt(propertyName, propertyValue);
		}
		return criterion;
	}
	
	/**
	 * 按属性条件列表创建Criterion数组,辅助函数.
	 */
	protected Criterion[] buildCriterionByPropertyFilter(final List<PropertyFilter> filters) {
		List<Criterion> criterionList = new ArrayList<Criterion>();
		for (PropertyFilter filter : filters) {
			if (!filter.hasMultiProperties()) { // 只有一个属性需要比较的情况.
				Criterion criterion = buildCriterion(filter.getPropertyName(), filter.getMatchValue(), filter.getMatchType());
				criterionList.add(criterion);
			}
			else {// 包含多个属性需要比较的情况,进行or处理.
				Disjunction disjunction = Restrictions.disjunction();
				for (String param : filter.getPropertyNames()) {
					Criterion criterion = buildCriterion(param, filter.getMatchValue(), filter.getMatchType());
					disjunction.add(criterion);
				}
				criterionList.add(disjunction);
			}
		}
		return criterionList.toArray(new Criterion[criterionList.size()]);
	}
}
